Integumentary system Flashcards
what is the name for skin
cutaneous
what is the largest organ
skin
how thick is skin
o.5mm on the eyelids and 4.0 mm on the heels
Epidermis
Superficial layer, thin, epithelial tissue. Densly packed layers of cells and appears darker
Dermis
Deep layer, thicker, connective tissue. very few cells and composed of collagen and elastic fibers
What is the dermis attached to?
The underlying fascia by a subcutaneous layer of areolar and adipose tissues
keratinocytes
90% of epidermal cells, produce keratin and lamellar granules and a barrier
lamellar granules
release water-resistant lipids
keratin
tough, fibrous protein
Langerhans cells
Migrate to the epidermis from red bone marrow and contributes to the bodys immune responses
Merkel cells
In the deepest layer of epidermis and hare contact specific sensory receptors (merkel discs) that detect touch sensations
Melanocytes
in the deepest layer of epidermis, produce melanin and slender projections transfer melanin to keratinocytes
How many layers in epidermis
4-5 layers of keratinocytes in various stages of development
Thin skin
4 layers, covers most of the body
thick skin
5 layers, covers areaas exposed to friction (palms, soles)
kerationcytes formed where
Formed in the deepest layer and slowly get pushed to the surface. They accumulate more keratin as the proceed and eventually undergo apoptosis before being sloughed off
Apoptosis
programmed cell death
Stratum basale
Single row of columnar keratinocytes that act as
stem cells
(continually undergo cell division to produce new cells)
Stratum Spinosum
Superficial to stratum basale. 8-10 layers of many-sided keratinocytes
stratum granulosum
superficial to stratum spinosum. 3-5 layers of flattened keratinocytes that undergo apoptosis. Production of keratin and lamellar granules
Stratum lucidum
4-6 layers of clear, flat, dead keratinocytes that have large amounts of keratin. Only in thick skin
Stratum corneum
Most superficial, 25-30 layers of flat dead keratinocytes that contain mostly keratin that are pushed to the skins surface. Superficial layers are continally sloughed off and replaced
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what is embedded in the dermis
hair follicles, glands, blood vessels ad tactile sensory receptors and nerve endings
papillary region
Superficial portion, areolar connective tissue and thin collagen/elastic fibers, projections into the epidermis called dermal papillae increase the dermal contact surface
Reticular region
Deep portion (thick), dense irregular connective tissue and thick collagen/elastic fibers, gives the skin its elasticity and extensibility
Hair
composed of circular columns of dead keratinized epidermal celles that bonded together by proteins
Shaft
Superficial portion that projects above the skin
root
deep portion that penetrates into the dermis
what composes the shat and root
concentric layers of cells. the Medulla, cortex and cuticle
Hair follicle
surrounds the root
hair follicle
Internal root sheath
cellular tublar sheath
hair follicle
external root sheat
Downward extension of the epidermis
dermal root sheath
A dense layer of dermis that surrounds the hair follicle
papilla
an indentation in the bulb of the base of a hair follicule
Papilla
hair matrix
produces cells that form the hair and internal root sheath
papilla
blood vessels
nourish the growing hair follicle
arrector pili muscle
smooth muscle that when contracted, causes the hair to erect on skin surface
hair root plexuses
Nerve ending. Sensory receptor stimulated when hair is moved.
Sebaceous (oil) glands
most open into hair follicules, not in palms or soles, release oily substance called sebum
Sebum
oily substance that keeps hair from drying, prevents water from evaportaing from skin, keep skin soft and pliable, inhibt growth of some bacteria
Sudorferous (sweat) glands
Release sweat into hair follicles or onto skin surface
Sudoriferous glands
Eccrine sweat glands
In most regions of body, sweat contains water, ion, urea and ammonia, elps regulate body temp
Sudoriferous glands
Apocrine sweat glands
Present in axilia, groin, breasts and face, sweat also contains lipids/proteins that are metabolized by bacteria (odour), starts functioning around pubery and stimulate dby emotional stress
nails
plates of tightly packed dead keratinized epidermal cells
nail body
Through epidermis, visible portion, free edge is white bc no underlying capillaries, lunula is white due to thick epithelium in the area
nail root
In the dermis, buried in a fold of skin, deep to the root is the nail matrix
nail matrix
germnal layer of cells that arise from the epidermis
Functions
keratin
protects skin and underlying tissue from external enviroment
Functions (protections)
lamellar granules
lipids are relased from lamellar granules prevent water from entering or leaving
Functions (protections)
melanin
absorbs harmgul UV light
Functions (protections)
langerhands cells and macrophages
assist in immunity
Functions of sudoriferous glands
evaporation of sweat to regulate body temp and eliminates wastes through sweat
functions, make vitamin D
UV light activates a precursor molecule produced in skin
Cutaneous sensation
Touch, pain and temp are detected by the various tactile receptors and nerve endings
